Electric bell with momentum action striker



Jan. 10, 1967 J. MALIN 3,298,020

ELECTRIC BELL WITH MOMENTUM ACTION STRIKER Filed Sept. 30, 1964 2 Sheets-Sheet 1 FIG.

INVENTOR )7 JACK Mil/IV ATTORN Y Jan. 10, 1967 ELECTRIC BELL WITH MOMENTUM ACTION STRIKER Filed Sept. 30, 1964 2 Sheets-Sheet INVENTOR JACK MAL/N ATTORNEY United States Patent C) 3,298,020 ELECTRIC BELL WITH MOMENTUM ACTION STRIKER Jack Malin, Beechhurst, N.Y., assignor, by mesne assignments, to Protective Alarm Devices Manufacturing Company, Inc., Kenilworth, NJ., a corporation of New York 4 Filed Sept. 30, 1964, Ser. No. 400,531 3 Claims. (Cl. 340-392) This invention relates to electric bells and, more particularly, to a novel electric bell including means providing free motion of a striker toward a gong and an improved and simplified construction of the operating arts.

p Electric bells of the type to which the present invention is directed generally comprise frame means, such as a metal housing or base member, mounting an electromagnetic operating mechanism and arranged to be secured to a suitable support surface. A cup-shaped gong is carried by the base member and at least partially embraces the latter. The electromagnetic operating mechanism includes an armature which operates a striker. When an operating potential is applied to a solenoid or electromagnet, the striker is moved by the armature in a direction to strike the gong and thus ring the bell.

The striker is usually an elongated member mounted for relative slidable movement with respect to the base member. Generally speaking, the range of movement of the striker toward the gong has been directly determined by the stroke of the armature actuated by the electromagnet or solenoid. Frequently, the armature brings the striker into full contact with the gong within the range of movement of the armature. Unless the range of movement of the armature is properly adjusted, and its adjustment maintained, the striker has a tendency either to tap the gong only lightly or else to be pressed against the gong and thus destroy the vibration of the gong.

It has therefore been proposed to provide a bell of this type in which the striker has a range of free movement in respect to the armature and upon actuation by the armature. In this type of arrangement, the striker extends through an aperture in the armature and has associated therewith a pair of coil springs each embracing the striker on a respective opposite side of the armature. These coil springs normally constrain the striker to move with the armature during actuation of the bell, but allow a free movement of the striker, due to its momentum under the impetus of the armature movement, toward the gong to strike the same, the coil springs then operating to restore the striker to its initial relation with respect to the armature.

Arrangements of this type have required special selection of the relative strengths of the two springs and careful adjustment of the springs in order to obtain proper operation of the bell. This selection and adjustment has been a disadvantage from the practical construction and operation standpoint.

In addition, electric bells are characterized by certain other disadvantages. For example, under certain conditions, the armature of the electromagnetic mechanism, when actuated, tends to freeze to the pole piece of the electromagnet. This has interfered with proper operation of the bell. A further disadvantage of known electric bells has been the necessity for substantially completely dismantling the bell in order to remove and replace either the armature or the striker or both.

Among other disadvantages of known electric bells is the tendency for the striker to bind in its guiding means, and the liability to freezing of the striker under conditions of relatively high humidity or in the presence of moisture, which results in rusting together of the parts so "ice that the striker either becomes inoperative or does not operate properly when the bell is actuated. Finally, known electric bells are characterized by relatively costly and expensive components and relatively expensive and time consuming assembly and adjustment operations.

Accordingly, it is an object of the present invention to provide an electric bell which is free of disadvantages of prior art bells and which has a novel spring arrangement for providing for limited free movement of a striker relative to an actuating armature therefor.

Another object of the invention is to provide such an electric bell in which the construction and assembly are greatly simplified as compared to the prior art bells.

A further object of the invention is to provide such an electric bell including a spring means for normally constraining the striker to move with the armature, while providing for free movement of the striker under the impetus imparted thereto by the armature, with this spring means further serving to prevent freezing of the armature to the pole piece of an electromagnet.

Yet another object of the invention is to provide an electric bell of the type just described including parts particularly designed for quick and easy assembly of the bell.

Still a further object of the invention is to provide such an electric bell in which the armature may be easily and readily disassembled without the necessity of removing a contact structure associated with the electromagnet means for operating the armature.

For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is an inside elevation view of an electric bell embodying the invention, and showing the parts in the rest position;

FIGS. 2 and 3 are sectional views taken on the correspondingly numbered lines of FIG. 1; and

FIG. 4 is a sectional view of the bell, taken on the line 44 of FIG. 2, but showing the positions of the bell components as the striker engages the gong.

Referring to the drawings, one form of electric bell embodying the invention comprises a generally cylindrical and cup-shaped frame meansor base member 10 whose cylindrical wall, adjacent its open end, is integral with a radially outwardly extending mounting flange 11 formed with uniformly spaced apertures to receive securing means for fastening base member 10 to a suitable support surface. A circular wall 12 of base member 10 is formed, eccentrically, with an outwardly projecting reinforced boss 13 having an outwardly opening tapped bore 14. Bore 14 receives a headed stud 16 which, in association with a locking washer 17, secures a metal gong 15 to base member 10. Gong 15 is also generally cup-shaped and substantially encloses the base member 10 and the parts associated therewith, while being free of contact with the base member at all points.

The circular wall 12 of base member 10 has mounted thereon a frame or bracket 20 forming part of the electromagnetic operating structure for the bell. Bracket 20 is formed of paramagnetic material such as, for example, ferromagnetic material including iron and suitable alloys of iron. As viewed in FIGS. 1, 3 and 4, bracket 20 includes a lower horizontal wall 21, a vertical wall 22, and an arm 23 extending forwardly from wall 22, adjacent the left-hand edge thereof and normal to wall 22. For a purpose to be described, the upper horizontal edge of arm 23 is formed with a relatively shallow substantially rectangular notch 24. Also for a purpose to be described, the left end of horizontal wall 21 is formed with an upwardly bent, apertured and projecting ear 26. Adjacent the left-hand portion of its upper edge, vertical wall 22 is formed with a generally horizontally and forwardly extending arm 33.

Intermediate its ends, wall 21 is formed with a pair of substantially circular apertures 27, also for a purpose to be described, and a third aperture 28 is formed adjacent the right-hand edge at wall 21. Rear wall 22 of bracket or frame 20 is formed with a pair of elongated slots 31 arranged to receive suitable fastening elements 32 for securing bracket 20 to circular wall 12 of base member 10.

Bracket 20 serves to support the electromagnetic operating mechanism for the bell as well as the contact and terminal means for such operating mechanism. The electromagnetic operating mechanism includes a pair of electromagnets or solenoids 40 each including a winding 41 wound on a spool 42 through which extends an electromagnetic core 43 having a reduced lower end 44 and an enlarged upper end constituting a pole piece 45. The relative polarities of the two electromagnets 40 are reversed, so that one pole piece 45 is a north pole and the other pole piece 45 is a south pole. However, the two windings 41 are connected in series with each other as will be noted from the interconnected leads 46, 46 of FIG. 1.

Electromagnets 40 are assembled to bracket or frame 20 by inserting the reduced lower ends 44 of cores 43 through the circular apertures 27 in lower wall 21 of bracket or frame 20. The electromagnets 40 are retained in position by means of push-on nuts which are slid up over the downwardly projecting reduced lower ends 44 and into engagement with the lower surface of wall 21. Similarly, cores 43 are retained in proper assembled relation wit-h spools 42 by means of push-on nuts 48 slipped over the pole pieces 45 and into engagement with the upper ends of spools 42.

The movable element of the electromagnetic structure comprises a paramagnetic armature 30 operatively associated with the pole pieces 45. Armature 30 is an essentially flat piece of paramagnetic metal which, adjacent its left end, as viewed in FIGS. 1 and 4, is enlarged to form a T-head 36 from which there projects a bent apertured ear 37. The opposite side edges of T-head 36 are formed with notches 38 which have a spacing between their inner ends of the order of the width of the notch 24 in the upper edge of arm 23. Thereby armature 30 may be pivotally mounted on arm 23 by nesting of T head 36 into notch 24 with the notches 38 embracing the material of arm 23 at each edge of notch 24. A tension coil spring 25 has its lower end hooked into the aperture in car 26 and its upper end hooked into the aperture in ear 37, so that coil spring 25 biases armature 30 to the rest position shown in FIG. 1, the movement of armature 30 in a counterclockwise direction being limited in a manner to be described.

Adjacent its right-hand end, as viewed in FIGS. 1 and 4, armature 30 is formed with an aperture 34 which, in the operative position of armature 30 shown in FIG. 4, is substantially vertically aligned with aperture 28 in wall 21 of frame or bracket 20. Apertures 28 and 34 have brass bushings or eyelets 35 anchored therein through which there extends, with clearance and for relatively easy sliding movement, a striker i). Striker 50 is relatively elongated, circular cross section rod of a suitable metal such as, for example, stainless steel or the like. The striker rod 50 extends not only through the brass bushings 35 in apertures 28 and 34 but also through an aperture 18 in the cylindrical wall of base member 10, aperture 18 being vertically aligned with aperture 28.

The lower end of striker 50 is preferably rounded, as indicated at 51 and is, in the rest posiiton of the bell, disposed at a distance from the rim of gong 15 which is slightly greater than the throw, or amplitude of the operating stroke, of armature 30. That is, when armature 30 occupies the operative position of FIG. 4, and

with striker 50 having the position relative to armature 30 as indicated in FIG. 1, the lower end 51 of the striker will not contact the rim of gonglS. However, means are provided for free movement of striker 50, under the im- :petus or momentum imparted thereto by operation of armature 30, so that, after armature 30 engages pole faces or pole pieces 45, striker 50 will continue its downward movement so that its lower end 51 will strike the rim of gong 15. This means will now be described.

At a short distance from its upper end, as viewed in FIGS. 1 and 4, striker 50 is formed with a circumferential groove which receives a C-clip or E-ring 52 constituting an abutment means on striker 50. A leaf spring 55, of nonferrous, nonmagnetic, or diamagnetic material, extends beneath armature 3b and has its inner end anchored thereto, by diamagnetic rivets 53, at a point on armature 36 intermediate the pole pieces 45. Adjacent its free end, leaf spring 55 is formed with a circular aperture 54 (FIG. 4) of substantially larger diameter than striker 50, so that striker 50 can extend freely through circular aperture 54. C-clip 52 anchored in the groove in striker 50, is above spring 55 and below armature 30 and, in the rest position of the bell, spring 55 extends in substantially flush relation along the undersurface of armature 30, for the major portion of its length, with its free end engaging the C-clip 52 and the latter engaging the upper bushing 35 in the aperture 34 in armature 30.

However, the relative mass and inertia of striker 50 is such that, when electromagnets 40' are energized to pull armature 30 toward pole pieces 45, the impetus thereby imparted to striker 50 causes the striker to keep moving after spring 55 is pressed by armature 30 into contact with the right pole piece 45, as viewed in FIG. 4. Therefore, striker 50 continues to move downwardly, bending the free end of spring 55 downwardly by virtue of engagement of C-clip 52 therewith, so that striker 50 has a free movement relative to armature 30. Lower end 51 of striker 50 thereupon strikes the rim of gong 15 and is substantially immediately retracted due to the force stored in spring 55 by virtue of the bending of the free end thereof. Such retraction will occur even if electromagnets 40 remain energized. As soon as electromagnets 40 are deenergized, due to opening of the energizing circuit therefor, the parts move back to the position illustrated in FIG. 1.

By virtue of the described construction, striker 50 is thus freely movable in the area where it engages gong 15. Thereby, a true ring is imparted to the gong, and has a sharp volume, as gong 15 is free to resonate and striker 50 merely strikes the gong a sharp impact and is then immediately retracted. There is no deadening of the sound of gong 15 and no possibility that only a light tap will be imparted to the going by striker 50. As a further feature, spring 55, which is preferably made of Phosphor bronze, acts as a shield to prevent freezing of armature 30 to pole pieces 45. As the spring 55 contacts rightrhand pole piece 45, it prevents armature 30 from contacting this pole piece and, due to the fact that armature 30 is thus spaced slightly above right-hand pole piece 45, in the position of FIG. 4, the armature is likewise spaced a short distance above the left-hand pole piece 45. This is an important feature of the invention.

The contact and terminalcomponents associated with the electromagnetic structure are supported upon the arm 33 extending forwardly from vertical wall 22 of bracket or frame 20 and parallel to wall 21. These components include a stack of substantially similar dielectric or insulating strips or blocks 56A through 56D, which are arranged one above the other with the lowermost strip or block 56A being in contact with arm 33. The strips 56A through 56D are anchored to arm 33 by means of bolts or anchor screws 57A and 57B with which are associated washers 58. Screw 57A may additionally have associated therewith a lock nut 59.

An elongated electrically conductive metal leaf spring 60 is anchored between the lowermost blocks or strips 56A and 56B, this spring having apertures therethrough whereby it is maintained out of electrical contact with the screws 57A and 57B. Contact leaf spring 60 has a movable contact 65 secured thereto intermediate its ends. A conductor 61 has one end soldered or brazed to the projecting left end of contact leaf spring 60, and its other end is connected to the upper end of the winding on the left-hand electromagnet 40. Between the dielectric strips 56B and 56C there is clamped a rearward projecting first terminal strip 62 of electrically conductive metal, and an input or signal lead 63 has one end anchored to strip, 62 and its other end arranged for connection to a bell control circuit. A forwardly projecting second terminal strip 64, of electrically conductive metal, overlies the upper surface of dielectric strip 56C. A second input or signal conductor 66 has a bare end soldered or brazed to strip 64 and its other end arranged for connection to the bell control circuit. A relatively rigid electrically conductive metal arm 67 overlies the upper surface of second terminal strip 64 and is held in electrically conductive contact therewith by virtue of the fact that strip 64 and arm 67 are clamped between the dielectric .strips 56C and 56D. A conductor 78 has a bared end connected to the second terminal strip 64, and a second end connected to the upper end of the winding on the right-hand electromagnet 40.

Arm 67 extends to the right parallel to armature 30 to a point somewhat beyond movable contact 65. The free end of arm 67 has a threaded aperture receiving a contact screw 68 on the lower end of which is a fixed contact 70 cooperable with the movable contact 65. Contact screw 68 has disposed thereon a lock nut 71 and a lock washer 72 whereby the position of fixed contact 79' may be adjusted and locked. Adjustment of contact screw 67, with concomitant adjustment of fixed contact 70, limits the upward movement of armature 30, as will now be described.

There are a pair of dielectric blocks or strips 73 and 74 anchored to the upper surface of armature 30 at a short distance inwardly from its free end, this anchoring being effected by rivets 76. Spacers 77 are interposed between blocks 73 and 74 to space the latter to form a slot 75 therebetween. The free end of contact leaf spring 60 is slightly bent and extends through the slot 75. Thus, contact leaf spring 60, by virtue of engagement of movable contact 65 with fixed contact 70, resiliently limits the upward movement of armature 30, under the influence of spring 25, and upon deenergization of electromagnets 40.

It should be noted that the armature assembly, including armature 30 and striker 50, may be readily disassembled from the bell without disturbing the contact structure. For this purpose, armature biasing spring is disconnected from one or the other of the apertured ears 26 or 37. T-head 36 of armature may thereupon be disengaged from notch 24 in arm 23, and armature 30 may be moved to the right to disengage the end of contact leaf spring 60 from slot 75, there being suflicient play between brass bushings and striker 50 to permit such movement. The entire armature assembly, including striker 50, thereupon may be removed for inspection, maintenance, or replacement. Due to the provisions of the push-on-nuts 47 and 48, assembly of the operating mechanism of the bell is greatly facilitated. By virtue of the leaf spring 55, which is made of Phosphor bronze or other suitable diamagnetic material, freezing of armature 30* to either of the pole pieces 45 is effectively prevented. Furthermore, the brass bushings 35 associated with striker 50' provide for easy motion, without any substantial friction, of striker 50 relative to bracket or frame 20 and armature 30, and furthermore prevent freezing of the striker to the magnetic structure.

It is believed that the operation of the bell will be readily understood from the foregoing description. Upon application of a potential between conductors 63 and 66, electromagnets are energized in series to attract armature 30 toward pole pieces 45. As the armature 36 moves downwardly, movable cont-act 65 remains in engagement with fixed contact 60 for certain time due to the flexibility of contact leaf spring 60. After a predetermined movement of armature 30, however, the contact 65 is separated from contact 70 to break the circuit and deenergize electromagnets 40. During such downward movement of armature 30, striker 50 is moved downwardly by virtue of engagement of C-clip 52 with the armature. As the armature reaches its limit of movement, when spring 55 is in engagement with right-hand pole piece 45, in the position of FIG. 4, striker 50, by virtue of its mass and the momentum imparted by the impetus given to it by the movement of armature 30, continues to move downwardly, deflecting spring 55. During this free movement, the lower end 51 of striker 50 strikes a sharp blow against gong 15, and striker 50 is immediately retracted by the energy stored in spring 55 due to the bending thereof.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. An electric bell comprising in combination, frame means; a gong carried by said frame means; a striker mounted on said frame means for movement in one predetermined direction to strike a preselected zone on said gong; electromagnetic operating means including pole piece means for said striker carried by said frame means and including a movable armature operatively associated with said striker and normally biased to a rest position; and a leaf spring secured at one end to extend along the surface of said armature facing said pole piece means and having a free end provided with an opening for movement of the striker therethrough, said free end, around the opening thus defined, thus straddling the striker, and abutment means on said striker between said armature and said spring, whereby; said leaf spring resiliently constrains said striker to move conjointly with said armature, and said armature, upon energization of said operating means, moving said striker in said one predetermined direction; the moving distance of the operating stroke of said armature moving said striker less than the distance to strike said gong; said striker, at the limit of the operating stroke of said armature and under the impetus imparted thereto during such operating stroke, deflecting the free end of said spring and continuing to move in said one predetermined direction to strike said gong; said spring, following striking of said gong by said striker, retracting said striker from said gong for movement, conjointly with said armature, to the rest position of said armature.

2. An electric bell comprising, in combination, frame means; a gong carried by said frame means; a striker mounted on said frame means for movement in one predetermined direction to strike a preselected zone of said gong; electromagnetic operating means for said striker carried by said frame means and including a pole piece and a relatively elongated armature movable relative 'to said pole piece, said armature being operatively associated with said striker and being normally biased to a rest position spaced from said pole piece; said armature, upon energization of said operating means, moving said striker in said one predetermined direction; and a diamagnetic metal leaf spring secured at one end to extend along the surface of said armature facing said pole piece, and having a free end operatively associated with said striker, said leaf spring resiliently constraining said striker to move conjointly with said armature; said armature, upon energization of said operating means, moving toward said pole piece to move said striker in said one predetermined direction, and said leaf spring preventing direct engagement between said armature and said pole piece; the amplitude of the operating stroke of said armature being insufliicent to strike said striker against said gong; said striker, at

the limit of the operating stroke of said armature and under the impetus imparted thereto during such operating stroke, deflect-ing said spring and continuing to move in said one predetermined direction to strike said gong;

said spring, immediately after said striker strikes said gong, retracting said striker to move, conjointly with said armature, to the rest position of the latter.

3. An electric bell comprising, in combination, frame means; a gong carried by said frame means; a striker mounted on said frame means for movement in one premetal leaf spring secured at one end to extend along the surface of said armature facing said' pole piece, and having a free end operatively associated with said striker,

- said leaf spring resiliently constraining said striker to move conjointly with said armature; said armature, upon energization of said operating means, moving toward said pole piece to move said striker in said one predetermined direction, and said leaf spring preventing direct engagement be tween said armature and said pole piece; the amplitude of the operating stroke of said armature being insuflicient to strike said striker against said gong; said striker, at the limit of the operating stroke of said armature and under the impetus imparted thereto during such operating stroke, deflecting said spring and continuing to move in said one predetermined direction to strike said gong; said spring, immediately after said striker strikes said gong, retracting said striker to move, conjointly with said armature, to the rest position of the latter.

4. An electric bell comprising, in combination, frame means; a gong carried by said frame means; a striker mounted on said frame means for movement in one predetermined direction to strike a preselected zone of said gong; electromagnetic operating means for said striker carried by said frame means and including a pole piece and a relatively elongated armature movable relative to said pole piece, said armature being operatively assoeiated with said striker and being normally biased to a rest position spaced from said pole piece; said armature, upon energization of said operating means, moving said striker in said one predetermined direction; and a Phos- V phor bronze leaf spring secured at one end to extend along the surface of said armature facing said pole piece, and having a free end operatively associated with said striker, said leaf spring resiliently oontraining said striker to move conjointly with said armature; said armature, upon energization of :said operating means, moving toward said pole piece to move said striker in said one predetermined direction, and said leaf spring preventing direct engagement between said armature and said pole piece; the amplitude of the operating stroke of said armature being insufficient to strike said striker against said gong; said striker, at the limit of the operating stroke of said armature and under the impetus imparted thereto during such operating stroke, deflecting said spring and continuing to move in said one predetermined direction to strike said gong; said spring immediately after said striker strikes said going, retracting said striker to move,

conjointly with said armature, to the rest position of the latter.

5. An electric bell comprising, in combination, a supa ferromagnetic bracket mounted on said support member and including a first support wall, a second wall extending perpendicularly to said first support wall, and

an arm extending f om 1 1 end of said second wall perport member, a gong carried by said support member; i

pendicular thereto and to said first wall, said arm having side edges parallel to said first wall and being spaced from said first wall; electromagnetic means, including pole piece means, mounted on said first support wall; an armature pivoted at one end on said arm and extending over said pole piece means and having a free end; means biasing said armature to a rest position spaced from said pole piece means; the free end of said armature being formed with an aperture and said support wall being formed with an aperture, and said apertures being substantially aligned with each other; a striker extending through said apertures for movement in a predetermined direction to strike a preselected zone of said gong; a leaf spring secured at one end to extend along the surface of said armature facing said pole piece means, and formed with an aperture at its free end through which said striker extends; and abutment means on said striker between said arm-ature and said spring, whereby said leaf spring resiliently constrains said striker to move conjointly with said armature; said armature, upon energization of said electromagnetic means, moving toward said pole piece means in an operating stroke to move said striker in said one predetermined direction; the amplitude of the operating stroke of said armature being insuflicient to strike said striker against said gong; said striker, at the limit of the operating stroke of said armature and under the impetus imparted thereto during such operating stroke, deflecting the free end of said spring and continuing to move in said one predetermined direction to strike said gong; said spring, following striking of said gong by said striker, retracting said striker from said gong for movement, conjointly with said armature, to the rest position of said armature. r

6. An electric bell, as claimed in claim 5, in which the edge of said arm more remote from said first support wall is formed with a rectangular notch; said armature being a substantially flat strip of ferromagnetic metal and having a pair of laterally spaced and laterally aligned substantially rectangular notches in its side edges adjacent its pivot end; the distance between the inner ends of said last-named notches being slightly less than the Width of said rectangular notch in the edge of said arm, whereby said armature has its pivot end resting in said rectangular notch with the notches in the armature embracing the portions of said arm on both sides of the notch in the latter.

7. An electric bell, as claimed in claim 6, including a second arm extending from the edge of said second wall and perpendicularly to the latter and parallel to said first support wall, said second arm being spaced from said first support wall a greater distance than the spacing of said fi-rst'mentioned arm from the latter; and a contact and terminal assembly for said electromagnet means mounted on said second arm; said armature being disengageable from said first-mentioned arm without disturbing said contact assembly.

8. An electric bell, as claimed in claim 5, including brass bushings inserted in the aperture in said support wall and in the aperture in the free end of said armature to facilitate motion of said striker relative to said armature and relative to said support wall.

9. An electric bell, as claimed in claim 5, in which said striker is formed with a circumferentially extending groove, said abutment means comprising a C-clip engaged in said groove.

References Cited by the Examiner UNITED STATES PATENTS 1,206,699 11/1916 Harthan 200 1,962,926 6/1934 Deary 340-392 2,522,664 9/1950 Coleman 340-392 3,043,995 7/1962 Cassell 340392 X NEIL C. READ, Primary Examiner.

D. L. TRAFTON, Assistant Examiner. 

1. AN ELECTRIC BELL COMPRISING IN COMBINATION, FRAME MEANS A GONG CARRIED BY SAID FRAME MEANS; A STRIKER MOUNTED ON SAID FRAME MEANS FOR MOVEMENT IN ONE PREDETERMINED DIRECTION TO STRIKE A PRESELECTED ZONE ON SAID GONG; ELECTROMAGNETIC OPERATING MEANS INCLUDING POLE PIECE MEANS FOR SAID STRIKER CARRIED BY SAID FRAME MEANS AND INCLUDING A MOVABLE ARMATURE OPERATIVELY ASSOCIATED WITH SAID STRIKER AND NORMALLY BIASED TO A REST POSITION; AND A LEAF SPRING SECURED AT ONE END TO EXTEND ALONG THE SURFACE OF SAID ARMATURE FACING SAID POLE PIECE MEANS AND HAVING A FREE END PROVIDED WITH AN OPENING FOR MOVEMENT OF THE STRINKER THERETHROUGH, SAID FREE END, AROUND THE OPENING THUS DEFINED, THUS STRADDLING THE STRIKER, AND ABUTMENT MEANS ON SAID STRIKER BETWEEN SAID ARMATURE AND SAID SPRING, WHEREBY; SAID LEAF SPRING RESILIENTLY CONSTRAINS SAID STRIKER TO MOVE CONJOINTLY WITH SAID ARMATURE, AND SAID ARMATURE, UPON ENERGIZATION OF SAID OPERATING MEANS, MOVING SAID STRIKER IN SAID ONE PREDETERMINED DIRECTION; THE MOVING DISTANCE OF THE OPERATING STROKE OF SAID ARMATURE MOVING SAID STRIKER LESS THAN THE DISTANCE TO STRIKE SAID GONG; SAID STRIKER, AT THE LIMIT OF THE OPERATING STROKE OF SAID ARMATURE AND UNDER THE IMPETUS IMPARTED THERETO DURING SUCH OPERATING STROKE, DEFLECTING THE FREE END OF SAID SPRING AND CONTINUING TO MOVE IN SAID ONE PREDETERMINED DIRECTION TO STRIKE SAID GONG; SAID SPRING, FOLLOWING STRIKING OF SAID GONG BY SAID STRIKER, RETRACTING SAID STRIKER FROM SAID GONG FOR MOVEMENT, CONJOINTLY WITH SAID ARMATURE, TO THE REST POSITION OF SAID ARMATURE. 